Patent Document 1 (Japanese Patent Application Laid-Open (JP-A) No. H11-171046) discloses a structure in which a sub-frame (a suspension member) and a main frame are joined at the front side and the rear side in the vehicle longitudinal direction. In this structure, a bracket that joins the sub-frame and the main frame at the rear side is provided, and a slit is formed in the bracket so that the sub-frame can move toward the vehicle rear side relatively with respect to the main frame. Due thereto, at the time of a vehicle front collision, the sub-frame is made to drop-down from the open portion at the rear end of the slit formed in the bracket.
In the structure disclosed in Patent Document 1 (JP-A No. 11-171046), the slit for causing the sub-frame to fall-out is formed in the bracket that joins the front sub-frame and the main frame at the rear side. However, a structure for facilitating dropping-out of the sub-frame is not provided at the joined portion that joins the front sub-frame and the main frame at the front side. Therefore, at the time of a vehicle front collision or at the time of a vehicle oblique collision, there is the possibility that the sub-frame will not be able to easily fall-out from the main frame.
In consideration of the above-described circumstances, an object of the present invention is to obtain a vehicle lower portion structure in which, at the time of a vehicle front collision or at the time of a vehicle oblique collision, efficiently rotates the rear portion side of a sub-frame toward the vehicle lower side with respect to a vehicle skeleton member.